1. Field of the Invention
The present invention relates to a portable electronic device having a first housing and a second housing foldable with respect to each other via hinges, and having a flexible wiring board which electrically connects a circuit board accommodated in the first housing to a circuit board accommodated in the second housing.
2. Description of the Related Art
Recent portable electronic devices, such as cellular telephones, mostly have an upper housing and a lower housing coupled in a foldable manner via hinges.
As disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2002-139024 and Unexamined Japanese Patent Application KOKAI Publication No. 2003-304310, for example, a hinge is covered with a hinge cover to improve the appearance of a portable electronic device. A circuit board accommodated in the upper housing is electrically connected to a circuit board accommodated in the lower housing by a flexible wiring board. The flexible wiring board is retained in the internal space covered with the hinge cover.
As disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-214927, for example, a flexible wiring board is led inside an upper housing and a lower housing via through holes respectively formed in the upper housing and the lower housing. A waterproof cap seal the through hole to prevent water permeation from the through hole.
With the flexible wiring board placed in the through hole, however, opening/closing the upper housing with respect to the lower housing deforms the flexible wiring board.
Therefore, repetitive opening/closing of the upper housing may cause the waterproof cap from coming off the through hole. The technology disclosed in Unexamined Japanese Patent Application KOKAI Publication No. 2004-214927 prevents the waterproof cap from coming off inward of the housing by forming a flange on the waterproof cap and engaging the flange with the outer surface of the housing. However, the waterproof cap may come off outward of the housing.
As a solution to this problem, another flange may be formed on the other side of the waterproof cap and engaged with the inner surface of the flange to prevent the waterproof cap from coming off outward. The additional flange however makes it difficult to fit the waterproof cap in the through hole.